Class or Template? Convert integers into decimal, octal, and hexadecimal.

Ok I started writting this as a class, then realized a template may be better.

What I need to do is take 3 numbers (10, 010, 0x10 for example) decimal, octal, and hexadecimal and then output the number in all 3 formats. If 0x10 was input then I would need to output that number in decimal, octal, and hexadecimal format.

Now I figure a template would be the best way to go since 3 different kinds of numbers will be getting input into the same function. But I am not sure how to handle the conversion of these numbers. I think there is something in the stream manipulation that can handle this, but I would appreciate some help figuring it out.

Also, I am not sure, but I think I would need to return an array from the function that held all three conversions of the number. I guess it would have to be a string array unless 0x10 (for example) can be held in a int array. This is also something I do not know how to do..I can do it in VB but not C++.

Any help is appreciated! :wave:

PHP Code:

---

template<class T>
string convertInt( const T )
{

//convert numbers to dec, hex and oct values and return all 3


}//end convertInt 


---

This is not somewhere you should use a template, since the numbers are always converted from strings to integers or the other way around.
In this case the easiest way would be to use the C sprintf/sscang functions, because they support the octal and decimal format:

Code:

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#include <cstdio>
#include <string>

std::string numberInThreeFormats(const std::string& str) {
    char buffer[255]; // large enough to hold any number three times
    int number;
    std::sscanf(str.c_str(), "%i", number); // %i = integer in decimal, octal or hexadecimal
    std::sprintf(buffer, "%d, 0%o, 0x%x", number, number, number); // %d = decimal, %o = octal, %x = hexadecimal
    return buffer;
}

---

All this is also possible using C++ iostreams for example, but you would have to do more work yourself.

Yah I have to use Iostream in C++ :(. But thanks for the post.

So does anyone know how to tell if a number is a decimal, hex or oct using iostream?

I need to input a number and tell if its a decimal, hex or oct and if so return what it is...if it isn't then return an error.

That is easy enough if I can figure out how to tell if the input is any of those or not.


Thanks! :wave:

You could first read it into a string, and then check if it starts with "0x" or "0".

cout << oct << number << hex << number << dec << number;

This is much work, how?

Well you see that only converts integers or doubles to into hex dec and oct.

I need to able to accept a hex dec or oct as input and then convert it to all three.

Since a hex (i.e. 0x10) cant be input as an integer or a double then it has to be a string. and those iostream functions do not work on strings.

how about doing the base conversion manually?
i=last,int b=1,a=0;
while(i>first)a+=*i--*b*=e1;
while(a)*j--=a%e2,a/=e2;

where first and last points to the first and last element in the char array to be converted from base e1 to base e2 in the char array j.

Why do something manually that you already have?

well depends, there are always special cases which can be optimised